HCC: Medium: Sound Rendering for Physically Based Simulation

计算物理可以帮助我们制作碰撞的刚体和变形物体的动画，或者破碎固体的动画，或者水花溅起的动画，但结果是无声电影。几乎不存在用于自动合成同步声音的实用算法。相反，录音是为预先制作的动画手动编辑的，或者在交互设置中自动触发。前者是劳动密集型和僵化的，而后者产生笨拙、重复的结果。这种情况严重阻碍了构建逼真的交互式模拟(无论是用于娱乐、培训还是其他应用程序)，这些模拟需要引人注目的声音。在这项研究中，PI将开始通过追求计算方法的基本进步来填补这一广泛的空白，同时解决几个特别具有挑战性的声音渲染问题。我们的目标是在这一领域产生一些第一批可行的方法，在此基础上可以建立更多的方法。这一计划的成功实施将从根本上改变我们与越来越令人信服的模拟现实的关系，因为我们将第一次能够听到和看到它们。为此，PI将开发基本算法，解决模拟产生声音的振动和计算这些振动产生的声场的问题。1)降阶振动模型。在复杂结构中模拟振动是昂贵的，因为既需要较高的模型复杂性，又需要音频速率的时间分辨率。PIS将开发降维模型方法，以实现从复杂的、非线性振动的几何形状(如薄壳)高效地呈现声音。逼真的声音需要在非常宽的可听频率范围内计算振动表面的辐射声场。但现有的方法要么对低频不准确，要么对高频不实用。PI将基于一个广泛的工具箱开发混合算法，并发现哪些方法对哪些问题最成功。作为算法工作的补充，PI将寻求一系列具有应用价值的困难、未解决的声音渲染问题的解决方案：a)和谐流体声音。很少有声音像倒一杯水或小溪流水那样与众不同，但目前还没有算法可以自动计算这些声音。PIS将研究基于谐波气泡的飞溅液体声辐射特性的实用算法。b)多目标声音。接触的物体的集合(想想一箱乐高积木或一篮子积木)发出的声音包含通常被忽略的近距离效果。PIS将开发声音渲染方法，以近似具有对象-对象交互的多对象接触声音。脆性断裂在玻璃破碎等破坏性过程中会产生独特的声音。PI将研究振动碎片的有效产生和激励，以及振动碎片的多目标声辐射。在本研究的所有方面，PI将通过将每个近似与参考解决方案进行比较来确保他们正在准确地解决问题，并且他们还将通过测试近似解、参考解决方案和记录声音之间的感知等价性来确保他们正在解决正确的问题。广泛的影响：该计划的成功实施将导致与计算机图形学直接相关的实用创新，以及声学模拟的应用。在未来，该项目中开发的方法或其后续方法将彻底改变在交互式虚拟环境中计算声音的方式。

Computational physics can help us animate crashing rigid and deformable bodies, or fracturing solids, or splashing water, but the results are silent movies. Virtually no practical algorithms exist for synthesizing synchronized sounds automatically. Instead, sound recordings are edited manually for pre-produced animations or triggered automatically in interactive settings. The former is labor intensive and inflexible, while the latter produces awkward, repetitive results. This situation is a serious obstacle to building realistic, interactive simulations (whether for entertainment, training, or other applications), which require sound to be compelling,. In this research the PIs will begin filling this broad void by pursuing fundamental advances in computational methods while solving several particularly challenging sound rendering problems. The goal is to produce some of the first viable methods in this area, upon which many more can be built. Successful implementation of this program will fundamentally transform our relationship with our increasingly convincing simulated realities, because for the first time we will be able to hear them as well as see them. To these ends, the PIs will develop fundamental algorithms that address the problems of simulating the vibrations that cause sound and computing the sound field produced by those vibrations.1) Reduced-order vibration models. Simulating vibration in complex structures is expensive because of the need for both high model complexity and audio-rate temporal resolution. The PIs will develop dimensional model reduction methods to enable efficient sound rendering from complex, nonlinearly vibrating geometry, such as thin shells.2) All-frequency sound radiation. Realistic sound requires computing the radiated sound field from a vibrating surface over the very broad range of audible frequencies. But existing methods are either inaccurate for low frequencies or impractical for high frequencies. The PIs will develop hybrid algorithms based on a broad toolbox and discover which methods are most successful for which problems.Complementing the algorithmic work, the PIs will pursue solutions to a series of difficult, unsolved sound rendering problems that are of value in applications:a) Harmonic fluid sounds. Few sounds are as distinctive as pouring a glass of water or the babbling of a brook, yet no algorithms exist to compute these sounds automatically. The PIs will investigate practical algorithms for harmonic bubble-based sound radiation characteristic of splashing fluids.b) Multi-object sound. Sounds made by collections of objects in contact (think of a bin of LEGOs or a basket of blocks) involve close-proximity effects that are often ignored. The PIs will develop sound rendering methods to approximate multi-object contact sounds with object-object interactions.c) Fracture. Brittle fracture creates distinctive sounds during destructive processes like breakage of glass. The PIs will research the efficient generation and excitation of vibrating fragments, and multi-object sound radiation from vibrating debris.In all aspects of this research, the PIs will ensure that they are solving problems accurately by comparing every approximation to a reference solution, and they will also ensure they are solving the right problems by testing perceptual equivalence between approximate solutions, reference solutions, and recorded sounds.Broader Impacts: Successful implementation of this program will lead to practical innovations of immediate relevance to computer graphics, and applications of acoustic simulation. In the future, the methods developed in this project or their successors will completely transform how sound is computed in interactive virtual environments.